Imaging device

Abstract

To provide an imaging device in which a focus detection pixel can be mounted even if pixels become smaller.SOLUTION: An imaging device includes: a first member that has a first opening through which light from a first microlens passes; a second member that has a second opening through which light from a second microlens passes, and which has an opening area smaller than that of the first opening; a first photoelectric conversion unit that converts light coming from the first opening into electric charges; a second photoelectric conversion unit that is arranged adjacent to the first photoelectric conversion unit along the row direction and converts light coming from the second opening into electric charges; a first signal output line that outputs a first signal; a second signal output line that outputs a second signal; and the wiring that is arranged between the first signal output line and the second signal output line along the row direction. The first photoelectric conversion unit is arranged between the first member and the first signal output line along an optical axis direction of the first microlens, and the second photoelectric conversion unit is arranged between the second member and the second signal output line along an optical axis direction of the second microlens.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an imaging device. [Background technology]

[0002] A front-illuminated image sensor having an imaging pixel and a pair of focus detection pixels in an area that is approximately the same size as one imaging pixel is known as a conventional technique (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-305010 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional front-illuminated image sensors such as those described in Patent Document 1, wiring for reading out signals from a photoelectric conversion unit must be formed on the incident light side of the light receiving unit, so the light receiving aperture must be set while avoiding that wiring, resulting in a narrower aperture for allowing light to enter the light receiving unit. As a result, in the case of focus detection pixels, which require a light receiving aperture (a pair of light receiving apertures) that is even smaller than that of normal imaging pixels, there is a problem in that it becomes difficult to incorporate focus detection pixels as the pixels become smaller. [Means for solving the problem]

[0005] According to a first aspect, an imaging element includes a first member having a first opening through which light from a first microlens passes; a second member having a second opening through which light from a second microlens passes, the second opening having an opening area smaller than that of the first opening; a first photoelectric conversion unit that converts light from the first opening into electric charges; a second photoelectric conversion unit arranged adjacent to the first photoelectric conversion unit in the row direction and converting light from the second opening into electric charges; a first signal output line that outputs a first signal based on the electric charges converted by the first photoelectric conversion unit; a second signal output line that outputs a second signal based on the electric charges converted by the second photoelectric conversion unit; and wiring arranged between the first signal output line and the second signal output line in the row direction, wherein the first photoelectric conversion unit is arranged between the first member and the first signal output line in the optical axis direction of the first microlens, and the second photoelectric conversion unit is arranged between the second member and the second signal output line in the optical axis direction of the second microlens. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a diagram showing a configuration of an electronic camera according to an embodiment; [Figure 2] FIG. 2 is a diagram showing a focus detection area on an imaging screen set on a planned imaging plane of an interchangeable lens. [Figure 3] FIG. 1 is a diagram showing a Bayer array of color filters. [Figure 4] FIG. 2 is a diagram showing a detailed configuration of an imaging element. [Figure 5] FIG. 2 is a diagram illustrating a structure of an imaging pixel. [Figure 6] FIG. 2 is a diagram illustrating a structure of a focus detection pixel. [Figure 7] FIG. 10 is a diagram for explaining a focus detection method using a pupil division method. [Figure 8] FIG. 1 is a diagram illustrating a basic pixel configuration of an image sensor. [Figure 9] FIG. 2 is a diagram for explaining wiring included in one pixel. [Figure 10] FIG. 2 is a diagram showing wiring in a wiring layer. [Figure 11] 1A to 1C are diagrams for explaining a manufacturing method of an imaging element. [Figure 12] 1A to 1C are diagrams for explaining a manufacturing method of an imaging element. [Figure 13] 1A to 1C are diagrams for explaining a manufacturing method of an imaging element. DETAILED DESCRIPTION OF THE INVENTION

[0007] An embodiment in which the present invention is applied to an electronic camera as an imaging device will be described. Figure 1 shows the configuration of the electronic camera of this embodiment. The electronic camera 101 of this embodiment is composed of an interchangeable lens 102 and a camera body 103, and the interchangeable lens 102 is attached to a mount portion 104 of the camera body 103.

[0008] The interchangeable lens 102 includes lenses 105 to 107, an aperture 108, and a lens drive control device 109. The lens 106 is used for zooming, and the lens 107 is used for focusing. The lens drive control device 109 includes a CPU and its peripheral components, and controls the drive of the focusing lens 107 and the aperture 108. detects the positions of the zooming lens 106, the focusing lens 107 and the aperture 108, and transmits lens information and receives camera information through communication with the control device of the camera body 103.

[0009] On the other hand, the camera body 103 is equipped with an image sensor 111, a camera drive control device 112, a memory card 113, an LCD driver 114, an LCD 115, an eyepiece 116, etc. The image sensor 111 is arranged at the intended imaging plane (intended focal plane) of the interchangeable lens 102, and captures an image of a subject formed by the interchangeable lens 102 and outputs an image signal. The image sensor 111 has imaging pixels (hereinafter simply referred to as imaging pixels) arranged two-dimensionally, and a row of focus detection pixels (hereinafter simply referred to as focus detection pixels) is incorporated in the portion of the imaging pixels corresponding to the focus detection position.

[0010] The camera drive control device 112 includes a CPU and its peripheral components, and performs drive control of the image sensor 111, processing of captured images, focus detection and focus adjustment of the interchangeable lens 102, control of the aperture 108, display control of the LCD 115, communication with the lens drive control device 109, and sequence control of the entire camera. The camera drive control device 112 communicates with the lens drive control device 109 via electrical contacts 117 provided in the mount unit 104.

[0011] The memory card 113 is an image storage that stores captured images. The LCD 115 is used as a display for a liquid crystal viewfinder (EVF: electronic viewfinder), and the photographer can view the captured image displayed on the LCD 115 through an eyepiece 116.

[0012] The subject image formed on the image sensor 111 after passing through the interchangeable lens 102 is photoelectrically converted by the image sensor 111, and the image output is sent to a camera drive control device 112. The camera drive control device 112 calculates the amount of defocus at the focus detection position based on the outputs of the focus detection pixels, and sends this defocus amount to the lens drive control device 109. The camera drive control device 112 also sends an image signal generated based on the outputs of the imaging pixels to an LCD driver 114 to display on an LCD 115, and stores the image in a memory card 113.

[0013] The lens drive control device 109 detects the positions of the zoom lens 106, the focusing lens 107, and the aperture 108, and calculates lens information based on the detected positions, or selects lens information corresponding to the detected positions from a pre-prepared look-up table, and sends the information to the camera drive control device 112. The lens drive control device 109 also calculates the lens drive amount based on the defocus amount received from the camera drive control device 112, and drives and controls the focusing lens 107 based on the lens drive amount.

[0014] The image sensor 111 is a back-illuminated 4TR-CMOS (Complementary Metal Oxide Semiconductor) sensor. The 4TR-CMOS sensor is composed of a photoelectric conversion unit and four transistors: a transfer gate transistor, a source follower transistor, a row selection transistor, and a reset transistor. Details will be described later.

[0015] 2 shows focus detection areas on an imaging screen G set on the intended imaging plane of the interchangeable lens 102. Focus detection areas G1 to G5 are set on the imaging screen G, and focus detection pixels on the image sensor 111 are arranged linearly in the longitudinal direction of each of the focus detection areas G1 to G5 on the imaging screen G. In other words, the focus detection pixel array on the image sensor 111 samples the image of the subject in the focus detection areas G1 to G5 formed on the imaging screen G. The photographer manually selects any focus detection area from among the focus detection areas G1 to G5 depending on the shooting composition.

[0016] FIG. 3 shows the arrangement of color filters installed on the image sensor 211. Color filters in the Bayer array shown in FIG. 3 are installed on the imaging pixels arranged two-dimensionally on the substrate of the image sensor 111. Note that FIG. 3 shows the color filter arrangement for four (2 × 2) imaging pixels, and an imaging pixel unit having this color filter array for four pixels is deployed two-dimensionally on the image sensor 111. In the Bayer array, two pixels having a G (green) filter are arranged in diagonal positions, and a pair of pixels having a B (blue) filter and an R (red) filter are arranged in diagonal positions perpendicular to the G filter pixels. Therefore, in the Bayer array, the density of green pixels is higher than the densities of red and blue pixels.

[0017] Fig. 4 is a front view showing the detailed configuration of the image sensor 111. Fig. 4 is an enlarged view of the periphery of one focus detection area on the image sensor 111. The image sensor 111 is made up of imaging pixels 210 and focus detection pixels 211 for focus detection.

[0018] Fig. 5(a) is a front view of an imaging pixel 210. Fig. 5(b) is a cross-sectional view taken along line AA in Fig. 5(a). The imaging pixel 210 is composed of a microlens 10, a microlens fixing layer 11, a color filter 12, a planarization layer 13, a light-shielding film 14A, a semiconductor layer 16, and a wiring layer 17. A photoelectric conversion section 15a and a channel stop section 15b are formed on one surface of the semiconductor layer 16.

[0019] The microlenses 10 focus light that reaches the surfaces of the imaging pixels 210 and direct it toward the photoelectric conversion units 15a. The microlens fixing layer 11 fixes the microlenses 10 to the color filters 12. The color filters 12 are resin layers that transmit light in specific wavelength ranges, and are made by dispersing pigments corresponding to each color (e.g., R, G, B) in resin, or by coloring resin with dyes corresponding to each color (e.g., R, G, B). The planarization layer 13 is a layer that planarizes the surface after the light-shielding film 14A is formed in the manufacturing process described below (see FIG. 12(b)) and before the color filters 12 are formed.

[0020] The light-shielding film 14A is a film for blocking light near the channel stop 15b, preventing noise generation and color mixing. The photoelectric conversion unit 15a photoelectrically converts the light that reaches it and accumulates signal charges. The channel stop unit 15b is formed at the boundary between two imaging pixels 210, and prevents the signal charges generated in the photoelectric conversion unit 15a from leaking into surrounding pixels. The wiring layer 17 has wiring such as signal output lines, power supply lines, reset control lines, transfer gate control lines, and row selection control lines, which will be described later. Details of the wiring will be described later.

[0021] FIG. 6(a) is a front view of the focus detection pixel 211. FIG. 6(b) is a cross-sectional view taken along line BB of FIG. 6(a). The focus detection pixel 211 is composed of a microlens 10, a microlens fixing layer 11, a transparent film 18, a planarization layer 13, a light-shielding film 14B, a semiconductor layer 16, and a wiring layer 17. A photoelectric conversion unit 15a and a channel stop unit 15b are formed on one surface of the semiconductor layer 16. The microlens 10, the microlens fixing layer 11, the planarization layer 13, the photoelectric conversion unit 15a, the channel stop unit 15b, and the wiring layer 17 have the same functions as those of the imaging pixel 210, and therefore their description will be omitted.

[0022] The light-shielding film 14B is formed with openings on the right or left half of the photoelectric conversion unit 15a shown in FIG. 6(b) so that incident light can strike it. The focus detection pixels 211a, which receive light on the right half of the photoelectric conversion unit 15a, and the focus detection pixels 211b, which receive light on the left half of the photoelectric conversion unit 15a, are arranged alternately. The output distribution of the focus detection pixels 211a and the output distribution of the focus detection pixels 211b are compared to calculate the amount of defocus. The transparent film 18 is a resin layer that transmits light of all wavelengths in the visible light range.

[0023] Next, a focus detection method will be described with reference to FIG. 7. In an embodiment of the present invention, focus is detected using a so-called split-pupil method. FIG. 7 is a diagram showing the output distribution of focus detection pixels 211 when the interchangeable lens 102 is out of focus. Curve 21 is a curve that shows the output distribution of focus detection pixel 211a. Curve 22 is a curve that shows the output distribution of focus detection pixel 211b. The focus detection pixels 211a and 211b are arranged alternately. Because curve 21 is shifted to the right of curve 22, it can be seen that the position of the focus detection pixel 211 is back-focused.

[0024] By multiplying the image shift amount between these two output distributions 21 and 22 by a predetermined conversion coefficient, it is possible to calculate the deviation (defocus amount) of the current imaging plane (the imaging plane at the focus detection position corresponding to the position of the microlens 10 on the intended imaging plane) from the intended imaging plane. When the interchangeable lens 102 is in focus, the curve 21 and the curve 22 will coincide.

[0025] The basic pixel configuration of the image sensor 111 will be described with reference to Fig. 8. As described above, the image sensor 111 is a back-illuminated 4TR-CMOS sensor, and each basic pixel 300 is composed of four transistors: a photoelectric conversion unit 33, a charge-voltage conversion unit 34, a transfer gate transistor 32, a source follower transistor 35, a row selection transistor 36, and a reset transistor 31. The basic pixel 300 is also connected to a signal output line VOUT, a power supply line Vdd, a reset control line φR, a transfer gate control line φTG, and a row selection control line φRS.

[0026] The reset transistor 31 resets the charge-voltage converter 34 to an initial potential. The transfer gate transistor 32 transfers the photoelectrically converted signal charge to the charge-voltage converter 34. As described above, the photoelectric converter 33 photoelectrically converts the light that reaches it and accumulates the signal charge. The charge-voltage converter 34 is a floating capacitance that converts the signal charge into an electric potential, and this floating capacitance is generated by a diode that functions as a capacitor. The source follower transistor 35 amplifies the change in electric potential of the charge-voltage converter 34 due to the accumulated charge. The row selection transistor 36 performs switching to select the basic pixel 300 to which the signal is transferred.

[0027] The signal output line VOUT is a wiring for transferring signals output from the basic pixel 300 and is connected to the drain of the row selection transistor 36. The power supply line Vdd is a wiring for supplying power for amplifying potential changes in the charge-voltage conversion unit 34 and is connected to the source of the reset transistor 31. The reset control line φR is a wiring for controlling the on / off of the reset transistor 31 and is connected to the gate of the reset transistor 31. The transfer gate control line φTG is a wiring for controlling the transfer of signal charges to the charge-voltage conversion unit 34 and is connected to the gate of the transfer gate transistor 32. The row selection control line φRS is a wiring for controlling the on / off of the row selection transistor 36 and is connected to the gate of the row selection transistor 36.

[0028] The wiring included in one pixel will be described with reference to FIG. 9. As shown in FIG. 9, the image sensor 111 has two signal output lines VOUT, two power supply lines Vdd, two reset control lines φR, two transfer gate control lines φTG, and two row selection control lines φRS in one row of pixels arranged in parallel, and four signal output lines VOUT in one column. This allows signals from multiple basic pixels 300 to be read out at once, thereby increasing the detection speed of the image sensor 111. Accordingly, the wiring included in one pixel 51, indicated by dotted lines in FIG. 9, includes not only wiring connected to the basic pixel 300 but also wiring connected to the basic pixel 300 of other pixels that is not connected to this basic pixel 300. As a result, the number of wirings included in one pixel is large.

[0029] With reference to FIG. 10, the wiring in the wiring layer 17 of the image sensor 111 will be described. FIG. 10(a) is a plan view of the wiring in the wiring layer 17 as viewed from the microlens 10 side. FIG. 10(b) is a cross-sectional view taken along CC in FIG. 10(a). As shown in FIGS. 10(a) and 10(b), the wiring in the wiring layer is formed in a grid pattern across three layers. As viewed from the photoelectric conversion unit 15a, four signal output lines VOUT and two bias lines Vb are formed in the first layer, and two power supply lines Vdd and two reset control lines φR are formed in the second layer. Two transfer gate control lines φTG and two row selection control lines φRS are formed in the third layer. The bias lines Vb are formed to prevent interference.

[0030] 10(b), the wiring layer 17 is formed on the side opposite the light incident side of the photoelectric conversion unit 15a, so that wiring can be formed freely without being restricted (constrained) by the position of the photoelectric conversion unit 15a. That is, in this embodiment, wiring can also be formed in an area that overlaps with the projection of the light receiving area of ​​the photoelectric conversion unit 15a when projected from the light receiving surface side of the image sensor 111. On the other hand, when the image sensor is a front-illuminated type, the wiring layer is formed on the light incident side of the photoelectric conversion unit 15a, so that wiring needs to be formed so as not to overlap with the light receiving area of ​​the photoelectric conversion unit.

[0031] Furthermore, in this embodiment, the wiring layer 17 of the imaging element 111 is not restricted by the position of the photoelectric conversion portion 15a, and therefore the wiring width can be increased to improve the signal transmission efficiency.

[0032] Next, a method for manufacturing the image sensor 111 according to the embodiment of the present invention will be described with reference to Figures 11 to 13. Figures 11 to 13 show the image sensor 111, particularly the focus detection pixel 211 portion.

[0033] As shown in FIG. 11(a), a P-type epitaxial layer 61 is formed on a semiconductor substrate 60, and a diffusion layer is formed on the surface of the P-type epitaxial layer 61 to form a photoelectric conversion section 15a, a channel stop section 15b, and other elements (not shown) that constitute transistors and the like. This P-type epitaxial layer 61 corresponds to the semiconductor layer 16. Next, as shown in FIG. 11(b), a silicon oxide film is formed by CVD and aluminum (Al) wiring is formed by sputtering repeatedly to form a wiring layer 17 on the P-type epitaxial layer 61. Then, as shown in FIG. 11(c), a support substrate 62 is bonded onto the wiring layer 17.

[0034] As shown in FIG. 12(a), the semiconductor substrate 60 is removed by etching. Next, as shown in FIG. 12(b), a light-shielding film 14B made of aluminum (Al) is formed by sputtering on the surface from which the semiconductor substrate 60 has been removed. Then, as shown in FIG. 12(c), in order to planarize the surface, a resin that forms a planarization layer 13 is uniformly applied onto the light-shielding film 14B, and then a transparent film 18 is formed. For example, the transparent film 18 is formed through the steps of applying a resin, drying the applied resin, pattern exposure, and development processing.

[0035] 13(a), a resin for forming the microlens fixing layer 11 is applied onto the transparent film 18, and then a resin for forming the microlenses 10 is applied and patterned into a desired shape by well-known lithography to form the microlens base 63. Next, as shown in FIG. 13(b), the microlens base 63 is heated and molded into a hemispherical shape using a hot plate or the like to form the microlenses 10. Then, the support substrate 62 is removed to complete the imaging element 111.

[0036] In the imaging pixel 210 portion, the color filter 12 is formed corresponding to the transparent film 18, and the light-shielding film 14A is formed corresponding to the light-shielding film 14B. The color filter 12 and the transparent film 18 are formed in the same process, and the light-shielding films 14A and 14B are formed in the same process.

[0037] In the imaging element, if the microlenses 10, the color filters 12, and the transparent film 18 can be formed, the microlens fixing layer 11 and the planarizing layer 13 may be omitted.

[0038] According to the embodiment described above, the following effects can be obtained. (1) The image sensor 111 is a back-illuminated type, and the multiple pixels arranged two-dimensionally include the image sensor 210 and the focus detection pixel 211. This allows the effective opening area of ​​the light-shielding film 14B of the focus detection pixel 211 to be large, making it possible to incorporate the focus detection pixel even if the pixel is miniaturized.

[0039] Furthermore, since the wiring layer is arranged on the side opposite to the light incident side of the photoelectric conversion unit 15a, the distance from the microlens 10 to the photoelectric conversion unit 15a can be shortened by at least the length of the wiring layer compared to a surface-illuminated type in which the wiring layer is arranged on the light incident side of the photoelectric conversion unit 15a, thereby improving the accuracy of focus detection.

[0040] (2) The focus detection pixel 211 includes a semiconductor layer 16 having a photoelectric conversion unit 15a formed on one surface and a light-receiving surface on the other surface, a light-shielding film 14B that blocks a portion of the light incident on the photoelectric conversion unit 15a, and wiring VOUT that reads out signals from the photoelectric conversion unit 15a, with the wiring VOUT formed on one surface of the semiconductor layer 16 and the light-shielding film 14B formed on the other surface of the semiconductor layer 16. This allows the distance between the microlens 10 and the photoelectric conversion unit 15a to be shorter (shallower) than in the case of a front-illuminated image sensor in which wiring must be formed between the microlens and the photoelectric conversion unit to read out signals from the photoelectric conversion unit, thereby improving focus detection accuracy.

[0041] (3) The focus detection pixel 211 does not read out signals from the photoelectric conversion unit 15a, but has wiring for reading out signals from the photoelectric conversion units of other pixels on one side of the semiconductor layer 16. This makes it possible to form wiring that reads out signals from multiple basic pixels 300 at once, thereby increasing the detection speed of the image sensor 111.

[0042] (4) The wiring is designed to overlap with the projection of the light receiving area of ​​the photoelectric conversion unit 15a projected from the light receiving surface side of the image sensor 111. This makes it possible to form many wirings in the focus detection pixel 211 and widen the wiring width without significantly increasing the number of wiring layers. On the other hand, if the image sensor is a front-illuminated type, the wiring must be formed so as not to overlap with the light receiving area of ​​the photoelectric conversion unit. Therefore, forming many wirings may require a large number of wiring layers or make it difficult to widen the wiring width.

[0043] (5) Because there is a high degree of freedom in the shape of the light-shielding films 14A and 14B, by considering the shape of the light-shielding films 14A and 14B, it is possible to improve the inter-pixel isolation performance of the imaging pixels and suppress crosstalk between pixels and the line crawl phenomenon caused by light leakage.

[0044] (6) The imaging element 111 is manufactured by forming a P-type epitaxial layer 61 on the surface of a semiconductor substrate 60, forming a photoelectric conversion unit 15a on the surface of the P-type epitaxial layer 61, forming a wiring layer 17 on the photoelectric conversion unit 15a, removing the semiconductor substrate 60 from the P-type epitaxial layer 61, forming light-shielding films 14A and 14B on the surface of the P-type epitaxial layer 61 from which the semiconductor substrate 60 has been removed, forming a transparent film 18 and a color filter 12 on the light-shielding films 14A and 14B, and forming a microlens 10 on the transparent film 18 and the color filter 12. This allows for efficient manufacture of a back-illuminated imaging element.

[0045] The above embodiment can be modified as follows. (1) The light-shielding films 14A and 14B may be provided with the functions of electrodes or wiring. This can improve the functionality of the image sensor. For example, this can enable high-speed pixel readout or independent pixel control. The light-shielding films 14A and 14B may be provided with any of the functions of a signal line (signal output line VOUT), a power supply line Vdd, a control line (reset control line φR, transfer gate control line φTG, row selection control line φRS), or a bias line Vb. This can prevent an increase in the number of wiring layers 17 when increasing the number of wirings to simultaneously read or control multiple pixels.

[0046] Furthermore, by providing the light-shielding films 14A and 14B with the functions of electrodes and wiring, the degree of freedom in separating signal lines, control lines, power lines, and bias lines can be increased. Among the signal lines, control lines, power lines, and bias lines, some are better formed away from other electrodes and wiring. By providing the light-shielding films 14A and 14B with the functions of such wiring and forming the other wiring in the wiring layer 17, the wiring can be formed away from each other. For example, if a signal line is formed near a control line, interference may occur. Therefore, by providing the light-shielding films 14A and 14B with the functions of one of the signal and control lines and forming the other wiring in the wiring layer 17, the signal line can be formed away from the control line.

[0047] In this case, a through hole penetrating the P-type epitaxial layer 61 may be formed by etching or the like, and this through hole may be used to form wiring for electrically connecting the photoelectric conversion unit 15a and other elements formed on the surface of the P-type epitaxial layer 61 to the light-shielding films 14A and 14B.

[0048] (2) In the above embodiments, the number of wiring layers in the wiring layer 17 is three, but the number of wiring layers is not limited to three. For example, the number of wiring layers in the wiring layer 17 may be increased up to ten to increase the number of pixels that can be simultaneously read or controlled. Unlike a front-illuminated imaging element, increasing the number of wiring layers does not increase the distance between the microlens 10 and the photoelectric conversion unit 15a. Furthermore, the number of wiring layers in the wiring layer 17 may be reduced to two to limit functionality and reduce manufacturing costs.

[0049] (3) The light-shielding films 14A and 14B may be floating, or a voltage may be applied to the light-shielding films 14A and 14B by applying a bias to the light-shielding films 14A and 14B or by fixing the light-shielding films 14A and 14B to a power supply. This makes it possible to increase or decrease the load capacitance and prevent interference.

[0050] (4) Although aluminum (Al), which has high reflectivity, is used as the material for the light-shielding films 14A and 14B, a metal with a reflectivity lower than that of aluminum (Al) may be used. For example, tungsten (W), titanium (Ti), or tin (Sn) may be used as the material for the light-shielding films 14A and 14B. This prevents light reflected from the light-shielding films 14A and 14B from entering the photoelectric conversion unit 15a and degrading the image quality of the image captured by the electronic camera 101. Furthermore, instead of tungsten (W), titanium (Ti), or tin (Sn), a metal with a reflectivity lower than the visible light reflectivity of tungsten (W), titanium (Ti), or tin (Sn) may be used.

[0051] Alternatively, the light-shielding films 14A and 14B may be made of an oxide or nitride that does not transmit light having a reflectance lower than that of aluminum (Al). For example, an oxide or nitride that does not transmit visible light and has a reflectance lower than that of tungsten (W), titanium (Ti), or tin (Sn) may be used. Examples of oxides include tungsten oxide, titanium oxide, and tin oxide. Examples of nitrides include tungsten nitride, titanium nitride, and tin nitride. The light-shielding films 14A and 14B are formed by CVD, sputtering, or the like after removing the semiconductor substrate 60 (see FIG. 12(a)).

[0052] (5) Although aluminum (Al), which has high reflectivity, is used as the material for the light-shielding films 14A and 14B, a resin that does not transmit light and has a reflectivity lower than that of aluminum (Al) may be used. For example, a photocurable resin containing a black pigment such as titanium black or carbon black, or a photocurable resin colored with a black dye may be used as the material for the light-shielding films 14A and 14B. This prevents light reflected from the light-shielding films 14A and 14B from entering the photoelectric conversion unit 15a. Furthermore, instead of a photocurable resin containing a black pigment such as titanium black or carbon black, or a photocurable resin colored with a black dye, a resin that does not transmit visible light and has a reflectivity lower than that of tungsten (W), titanium (Ti), or tin (Sn) may be used. The light-shielding films 14A and 14B are formed, for example, after removing the semiconductor substrate 60 (see FIG. 12(a)), through the steps of applying a resin, drying the applied resin, pattern exposure, and development processing.

[0053] (6) A metal film having a predetermined reflectance lower than that of aluminum (Al) may be formed on the surface of the light-shielding films 14A and 14B. For example, a tungsten (W), titanium (Ti), or tin (Sn) film may be formed on the surface of the light-shielding films 14A and 14B. This prevents light reflected by the light-shielding films 14A and 14B from entering the photoelectric conversion unit 15a. Alternatively, instead of tungsten (W), titanium (Ti), or tin (Sn), a metal film having a reflectance lower than that of tungsten (W), titanium (Ti), or tin (Sn) for visible light may be formed on the surface of the light-shielding films 14A and 14B.

[0054] Alternatively, an oxide or nitride film that does not transmit light below a predetermined reflectance lower than that of aluminum (Al) may be formed on the surface of the light-shielding films 14A and 14B. For example, an oxide or nitride film that does not transmit visible light and has a reflectance lower than that of tungsten (W), titanium (Ti), or tin (Sn) may be formed on the surface of the light-shielding films 14A and 14B. Examples of oxides include tungsten oxide, titanium oxide, and tin oxide. Examples of nitrides include tungsten nitride, titanium nitride, and tin nitride. These films are formed by CVD, sputtering, or the like after the light-shielding films 14A and 14B are formed (see FIG. 12(b)).

[0055] (7) A resin film that does not transmit light and has a reflectance lower than that of aluminum (Al) may be formed on the surface of the light-shielding films 14A and 14B. For example, a photocurable resin film containing a black pigment such as titanium black or carbon black, or a photocurable resin film colored with a black dye may be formed on the surface of the light-shielding films 14A and 14B. This prevents light reflected from the light-shielding films 14A and 14B from entering the photoelectric conversion unit 15a. Instead of a photocurable resin containing a black pigment such as titanium black or carbon black, or a photocurable resin film colored with a black dye, a resin film that does not transmit visible light and has a reflectance lower than that of tungsten (W), titanium (Ti), or tin (Sn) may be formed on the surface of the light-shielding films 14A and 14B. These films are formed, for example, by forming the light-shielding films 14A and 14B (see FIG. 12(b)), and then going through the steps of applying a resin, drying the applied resin, pattern exposure, and development treatment.

[0056] (8) A film made of a material having a reflectance equal to or lower than the predetermined reflectance may be formed on the surface of the light-shielding films 14A and 14B, which further prevents light reflected by the light-shielding films 14A and 14B from entering the photoelectric conversion unit 15a.

[0057] (9) The image sensor 111 is a 4TR-CMOS sensor, but is not limited to a 4TR-CMOS sensor as long as it is a back-illuminated image sensor. For example, it may be another CMOS sensor or a CCD (Charge Coupled Device).

[0058] It is also possible to combine one or more of the embodiment and the modified examples. It is also possible to combine the modified examples in any way.

[0059] The above description is merely an example, and the present invention is not limited to the configuration of the above embodiment. [Explanation of symbols]

[0060] 10 Microlenses 11 Microlens fixing layer 12 color filters 13 Planarization layer 14A, 14B Light-shielding film 15a, 33 Photoelectric conversion unit 15b Channel stop section 16 Semiconductor layer 17 Wiring layer 18 Transparent membrane 31 Reset transistor 32 Transfer gate transistor 34 Charge-voltage conversion unit 35 Source follower transistor 36 Row select transistor 60 Semiconductor substrate 61 P-type epitaxial layer 62 Support substrate 101 Electronic Camera 102 Interchangeable Lenses 111 Image sensor 210 imaging pixels 211, 211a, 211b focus detection pixels 300 basic pixels

Claims

[Claim 1] a first member having a first opening through which light from the first microlens passes; a second member having a second opening having an opening area smaller than that of the first opening, through which light from the second microlens passes; a first photoelectric conversion unit that converts light from the first opening into an electric charge; a second photoelectric conversion unit arranged adjacent to the first photoelectric conversion unit in the row direction and configured to convert light from the second opening into electric charges; a first signal output line through which a first signal based on the charges converted by the first photoelectric conversion unit is output; a second signal output line through which a second signal based on the charges converted by the second photoelectric conversion unit is output; a wiring arranged between the first signal output line and the second signal output line in the row direction; Equipped with the first photoelectric conversion unit is disposed between the first member and the first signal output line in the optical axis direction of the first microlens, the second photoelectric conversion unit is disposed between the second member and the second signal output line in the optical axis direction of the second microlens. Image sensor.

Images